The invention is directed to measuring the amount of remaining grain (fuel) in a solid state or hybrid rocket motor during burn and more particulary to a means for continually monitoring the amount of remaining grain in solid state rockets and in the case of hybrid motors to control the mixture ratios and propellent utilization by fiber-optic means.
Presently there is no means for monitoring the grain regression rate in solid state or hybrid rocket motors due to the high temperature of the grain burn and the harsh environment. Any useful sensor must be either extremely durable, non-intrusive, or sacrificial; and not hamper the reliability or safety of the motor itself.
There has not been a suitable means for monitoring or controlling the burn of either solid state or hybrid rocket motors until the emergence of the present invention. The present invention will fill a long felt need for monitoring the burn rate and the amount of remaining grain in solid state and hybrid rocket motors and will find wide acceptance in the industry.